It's unclear how recent terror attacks in the U.K. will influence the election results.

Neither May nor Corbyn has the strongest record on the issue. May oversaw cuts to police forces while she was home secretary, and Corbyn has voted against several counter-terror laws in Parliament.

Brits head to the polls Thursday. Whichever party wins the majority will only have 11 days before it needs to start negotiating the U.K.'s divorce from the European Union.

If the election results in a hung Parliament, meaning no party wins a majority, a coalition government would need to be formed. That basically means parties would need to come together to form a majority. The last time this happened was 2010.